only trigger if the editor is still attached to the textarea, fixes #3440

Closes #3440

Merge request studip/studip!2338

resources/assets/javascripts/lib/wysiwyg.js

@@ -213,8 +213,11 @@ function enhanceEditor($textarea, ckeditor) {
     // make sure HTML marker is always set, in
     // case contents are cut-off by the backend
     $textarea.closest('form').submit(() => {
-        ckeditor.setData(wysiwyg.markAsHtml(ckeditor.getData()));
-        ckeditor.updateSourceElement();
+        // only trigger if the editor is still attached to the textarea
+        if (getEditor($textarea[0]) === ckeditor) {
+            ckeditor.setData(wysiwyg.markAsHtml(ckeditor.getData()));
+            ckeditor.updateSourceElement();
+        }
     });
 
     // focus the editor if requested